function sweep

  warning('off', 'all');
  n = 1000;
  step = 1.0/n;
  res = zeros(n,n);
  parfor_progress(n*n*0.8*0.8); 
      f = fopen('res_incr.txt', 'w');
      fclose(f);
  parfor i=1:n
    for j=1:n
      res(i,j) = v(step*i, step*j);
      f = fopen('res_incr.txt', 'a');
      fprintf(f, '%d %d %f\n', i, j, res(i,j));
      fclose(f);
      %c
      %disp('%f\%', c/n/n*100);
      parfor_progress
      if (step*j > 0.8)
        break;
      end
    end
    if (step * i > 0.8)
      continue;
    end
  end
  warning('on', 'all');
  parfor_progress(0);
  save('res.mat', 'res');
  keyboard()
end
